We wanted a band that never runs out of good ideas.
Most music software hands you a blank grid and wishes you luck. Septet starts somewhere better: with seven players who already know how to listen to each other. You don't draw the notes — you turn knobs that change what each player is trying to do, and the band works the rest out between themselves, in tune and in time, every single time.
“A tune is a recipe, not a recording — so the one you loved at 2am is still there, exact to the note, in the morning.”
It began with a confession. While building an earlier version of this engine, the maker kept getting stuck — not debugging, just listening, enjoying tunes that a machine had written a moment earlier. A procedural generator that turns out thousands of genuinely good tunes is a strange and rare thing. Strange enough to feel a duty to carry it through.
The whole thing rests on one stubborn idea: a tune is a recipe, not a recording. Give the engine a seed and a handful of settings and it grows the same song every time — same melody, same changes, same fills. That determinism is the point. A tune you keep is a few bytes of recipe, not a few megabytes of audio, and it never rots: the same seed always rebuilds it.
We built it as a rack because that is how the ideas actually relate. Everyone listens to everyone, the way players in a room all hear each other. Chords set the harmony the others read; drums lay the pocket the bass locks into; the melody asks a question and answers it four bars later. One faceplate per player, one colour per musical concern — the model you can hear made into a model you can see.
And it had to be honest. No stock loops, no hidden sample packs, no “AI” doing something it won't explain. Every note comes from rules you can read in the docs, voiced by a synth you can choose — your browser's own, or a SID and NES engine that sound like the chips they're named after. The machine shows its working. That is the studio we wanted to sit down at, so we built it and dressed it as the room it lives in.
Who makes it
Septet is made by one person: a self-described rack romantic who would rather build the studio than buy the plug-in. The engine is a clean Ruby library — the music theory written out as code you can read — wrapped in a bog-standard Rails app, with the browser doing nothing but playing the finished score. It is built engine-first and in the open: the theory is the product, and the interface grew out of it, not the other way around.
It is a slow, deliberate project, tuned by ear. Every change is judged the only way music can be — by sitting down, throwing the power, and listening to whether the band still sounds good.
— built in the studio, one seed at a time.
- Engine
- Deterministic band model · seven players on one shared score graph
- Stack
- Ruby music-theory core · Rails 8 · Hotwire · theory stays on the server
- Synths
- WebAudio (default) · SID 6581 · NES 2A03 chiptune voices
- Colour
- Ten musical concerns → ten signature hues (the facet language)
- Type
- Silkscreen labels · phosphor figures · this serif, the reading voice
Curious how the band actually works?